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Common Use:
To assist in diagnosing metabolic disorders that result in metabolic acidosis and electrolyte imbalance such as severe dehydration.

Serum for electrolytes (sodium, potassium, chloride, and carbon dioxide) collected in a gold-, red-, or red/gray-top tube. Plasma collected in a green-top (heparin) tube is also acceptable.

Normal Findings:
(Method: Anion gap is derived mathematically from the direct measurement of sodium, chloride, and total carbon dioxide.) There are differences between serum and plasma values for some electrolytes. The reference ranges listed are based on serum values.

AgeConventional and SI Units
Child or adult8–16 mmol/L

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